I happen to be a little cautious to keep my ek in topnotch condition, if you are not, you may discontinue reading right away, u might get bored.
anyhow, Fault code P0420 comes from catalytic converter removal. in foreign you can have around 5000$ fine if you hv removed the catalaytic converter (cat).
it may or maynot trigger SES(service engine soon) or CEL (Check Engine light). in mycase it had not triggered CEL, but i came to know it from ODB2 monitoring via ELM327 scantool. a must-have for any ek or even any jdm owner. easily available these days, even i saw some good fellows on pakwheel are also helping by selling it at a very nominal rate.
after removal of my ek's cat a few weeks ago, i felt it was running rich, i was too busy to match logged data with previous, this weekend, when i compared it, i was shocked, the air to fuel ratio was way too rich than 14.7:1 (the ideal)
i embarked on solving it myself.
there are three solutions to remove P0420 & return to normal air-fuel ratio after a cat removal:
1. replace cat, either buy it new, or get it from scrapyard, if not, then import, anyway replace it.
- fool the bank1 O2 sensor by moving the heated O2 sensor out of the direct throughput of exhaust pipe about an inch.
The sensor will not see cat removal by sensing less gasses and send all-ok report to ecu. b/t/w heated O2 sensor is the post-cat, in-exhaust oxygen sensor visible near bumper from underside, diagonally connecting to exhaust.
the way to do it is to remove and put it in an extender and connect extender to the exhaust. i chose that method, and more on that in next paragraphs.
- fool the ecu by modding the sensor wiring / overriding the values sent by sensor / sending favorable values to the ecu. i.e fool the ecu to see normal values, while sensor sends faulty values and midway you change them by electronics.
i have all the materials, tools and the data on that one too,
and if choosing 2nd method does not give me best results, i will go for it. and if not, then onto the 1st one.
i sorted these solutions from cost effectiveness point of view, the 3rd one, i.e modding the wires was most cheaper, components cost PKR 10 from proper place, i ve bought them, and if you can spare an hour, u can do it easily.
then i sorted these solutions from risk point of view. the 2nd one got my focus because moving the sensor a few inches away will not at all harm anything, and if that did not help, i can always remove the extender, or choose other methods.
lastly i sorted these solutions from quality point of view, and the 1st one is the ultimate choice if these two did not help but acquiring the catalytic converter of ek, here in Pakistan, and that also in an affordable price, is heck of a game.
b/t/w it costs around PKR 7k-10k at scrapyards, and that also very very bad conditioned. n ofcourse u need time and get your hands black to find goodones among the badones.
Practical / hands-on / real world issues
initially i have chosen solution 2, the extender.
the whole game is to restrict the exhaust gas flow in the sensor and hence less temperature, resulting the sensor send all-ok report.
on a good sunny day (that's today morning) when i had a couple of hours to myself, i jacked ek up about 6 inches and whacked the sensor open, it was jammed ofcourse, a couple of squirts of rust-remover spray helps and torqueing it atlast opened it. (many a times during torqueing it, i thought to leave away the fuss, because i am not accustomed to under-car makenkian. but it suddenly opened. thanks to ALLAH, otherwise i was off.
My half-**** research had told me that spark-plug-defoulers/adapters will easily fit as extenders.
I had pre-obtained them also and merily got them drilled and upto my understanding pre-ready to be fitted, all done yesterday.
after opening the sensor this morning, with a lot of effort, when i was just ready to fit the extender, i discovered that extender i had was way too smaller in dia than the sensor, i.e it was 14mm and sensor was 18mm. wtf. extenders wasted.
the defoulers used in foreign are mostly in american cars where the sparkplug thread size is 18mm, while here and in jdm, ALL sparkplugs are 14mm threaded.
now i had no choice but to find a way to obtain/make/lathe an extender. it took me more than 4 hours to figure out the exact bolt to fit in the home of sensor.
all the knowledge gained today is just this line: "Heated O2 sensor thread size is M18x1.5", u need to tell the hardware storekeeper that you need "18x1.5 da 2 inch ala kaabla te nut".
in return, on the cost of anywhere around 50-100PKR you will be handed over a fairly fat bolt and nut on it.
i ve made it upto this part, the kabla thing. tomorrow i ll move on to the following part.
you need to take it to a good machinist to:
a) weld the nut on top of head of nut and
b): then chuck in lathe, afterwards drilling a 12-14mm drill in it. [not all the way through, but leaving an mm or two,
c):then drill a 3mm hole in nut at the end.
lathe operation will cost u around 3-400 PKR
...... there u go, u ve got an extender. put sensor in it, and put the extender in the exhaust, volla u got your sensor fooled, the values returned to normal and hence the air-fuel mixture back on track. - the last line will be verified tomorrow, and IA i ll share it here that i got success or failure.
a truly painful thing, u know, the cat-removal. after all cats are there to protect. when u mess with them, they mess with you.
in our part of the Asian region, we use char so bees for a corrupt entity. ... the fault code a car gets after cat-removal; for polluting environment; is P0420, the 420 code, mtlb gardi 420 ho gyi hay, isko set karein.